Need Assistance In Motor Selection Please!

[Murocflyer]

The gents on RCG have found two gearboxes that may be suitable for use. My gearbox hunt thread can be found here: http://www.rcgroups.com/forums/showthread.php?t=2194033

1) http://www.allerc.com/hyperion-aluminum-hi-watt-gearbox-400-v2-p-1579.html

2) http://www.bphobbies.com/view.asp?id=V714915&pid=V751703

And I discovered the following:

3) http://www.astroflight.com/motor-accessories/gear-boxes.html

4) http://www.icare-icarus.com/Planetary-Gearboxes_c_51.html

5) http://www.e-fliterc.com/Products/Default.aspx?ProdID=EFLM206

 

[Murocflyer]

Frank, I'll be Frank with you (couldn't resist....) and say that the Motrolfly motors from Ken are about the BEST out there, and I've used just about all of them.

Usually, he charges an extra $30 to rewind a motor. I'd send him an email directly for a final price quote.

Thanks for the feedback Gary and please let me know what you find out. If he has questions about specifics/needs, have him email me or just let him know that I'm looking at motor capable of using a 3s or 4s LiPo and I'd like to get 30 minutes of flight on a 2200 mAH battery and to help with the long distance being covered I'd like to get at least 40 mph ground speed from the setup.

I truly appreciate the assist with this Gary and everyone else's help as well. This forum has been awesome in its help and assistance. I appreciate it and I know the RC community appreciates it as well.

Standing by.

Frank

 

[gyro]

Thanks for the feedback Gary and please let me know what you find out. If he has questions about specifics/needs, have him email me or just let him know that I'm looking at motor capable of using a 3s or 4s LiPo and I'd like to get 30 minutes of flight on a 2200 mAH battery and to help with the long distance being covered I'd like to get at least 40 mph ground speed from the setup.

I truly appreciate the assist with this Gary and everyone else's help as well. This forum has been awesome in its help and assistance. I appreciate it and I know the RC community appreciates it as well.

Standing by.

Frank

Frank, probably better for you to explain everything to him yourself: subsonicplanes@yahoo.com or via his website: www.subsonicplanes.com

I'm positive he'll be happy to help you. Personally, I'd rather put my eggs into the direct drive basket. Less moving parts = less to break. Additionally, if I'm going to add extra weight, I'd rather do it in mAh

Good luck, and thanks for the kind words!

-G

 

[Murocflyer]

Frank, probably better for you to explain everything to him yourself: subsonicplanes@yahoo.com or via his website: www.subsonicplanes.com

I'm positive he'll be happy to help you. Personally, I'd rather put my eggs into the direct drive basket. Less moving parts = less to break. Additionally, if I'm going to add extra weight, I'd rather do it in mAh

Good luck, and thanks for the kind words!

-G

I agree with your direct drive rationale. If possible, it would be much simpler to go with that. I'll contact Ken shortly and see what he can do.

Thanks again and as always, appreciate the prompt assistance and info.

Frank

 

[Aeroplayin]

My suggestion would be to do the calculations or ask someone who understand the difference between geared and direct drive. Since two of your criteria are to fly for 30 minutes and achieve 40 mph, geared motors give you the ability to gain a lot more efficiency out of bigger props. If you ever see a human powered aircraft, there is a reason for the big, slow spinning props. Efficiency. This is not about acceleration of air, but volume of air being moved.

It can be done on direct drive, I think, but your problem will be in maintaining the RPMs needed to achieve 40 mph for 30 minutes. Guys like Gary and me have rarely flown an electric powered plane for more than 8 minutes, so our mindset is different. But a 6.6 gear ratio will translate less energy to a bigger prop for more efficiency, which means more speed and longer flight times.

 

[Murocflyer]

Understand and that may be the way we go. If Ken can't do what we need, I'll ramp up my search again for a geared system. The only decent geared system that I could find was using a 3s though. Neu motors makes the best geared systems on anything higher but they are extremely expensive. If anyone knows of a geared system that I missed with a 6:1 ratio please let me know. I think I reached the end of the internet looking for them. :facepalm:

Speaking of human powered flight, I saw the Gossamer Condor in person fly and that was amazing.

Frank

 

[Aeroplayin]

To help things along, Frank, here is the online calculator I programmed that Gary was referring to. http://rcwebclub.com/PropEngine.aspx

If to calculate the gear ratio into the Kv, it will help you. For eample...

put 16 in the prop diameter field, 8 in the pitch field, the geared Kv (or for example, 2800Kv divided by 6.6 is 424 so put 424 in the Kv field), 3 in the cells field, leave volts at 3.7 per cell, 2200 in the mAh field, 1.13 pound in the weight field, select a temp from the menu, use 35 for the throttle setting, leave the Kv efficiency at 80%, and change the pK to 1.01. This will start you off in the right direction. From here you can play with different motor Kv's gear ratios, and prop sizes. Good luck!

Jim

 

[Aeroplayin]

I think the 6.6:1 ratio for 2800 is actually 368, so to get the Kv of the motor that will deliver 425 Kv at the prop, you need to multiply by 7.6... thus 2975 Kv. So this is how you can figure out the Kv you need at the prop, then do the math to figure out what real motor Kv you need or which gear box to use.

 

[Murocflyer]

Jim,

Thanks for the explanation on how to figure out the gear ratio for your calculator. I was playing with that the other morning and I didn't know how to do it on there. That's definitely good to know especially know.

I heard back from Ken and he is too busy to wind a custom motor for us. So now I need to nail down what motor and gearbox will work best. I can't afford to buy multiple motors, unfortunately.

Thanks again for the calculator tutorial. I'll be needing it.

Frank

 

[Murocflyer]

Data storage log:

3s inrunners

20 mm

http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXLWW9 2mm shaft, 65 g 3500 kv
http://www.e-fliterc.com/Products/Default.aspx?ProdID=EFLM1100 2mm shaft, 68g, 4200 kv
http://www.maxxprod.com/pdf/HA2025-xx00.pdf 2mm shaft, 65g, 3200 & 4200 kv
http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXDAYD&P=7 2mm shaft, ??g, 4100 kv
http://www.leopardhobby.com/proviewen.asp?id=1080&sid=37&gid=73&pt=3 2.3mm, 65g, 4450 kv
http://www.hobbyexpress.com/20mm_kv_4700_inrunner_brushless_motor_3068_prd1.htm 2.3mm shaft, ??g, 4700 kv

22mm

http://www.allerc.com/hyperion-y-22-long-motor-3600-kv-p-1825.html 2.3mm shaft, 70g, 3600 kv

24 mm
http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXLWX2 3mm shaft, 67g, 3180 kv
http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXLWX4 3mm shaft, 67g, 4040 kv


4s inrunners

20 mm
http://www.leopardhobby.com/proviewen.asp?id=1080&sid=37&gid=73&pt=3 2.3mm shaft, 65g, 2600 kv

24 mm
http://www.leopardhobby.com/proviewen.asp?id=1081&sid=37&gid=74&pt=3 2.3mm shaft, 73g, 4000kv